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(1) Field of the Invention
This invention relates to the repair of dents and other deformities in sheet metal, and more particularly to tools and methods which can be effectively used in the art of dent repair, that is, a specialized technique of metalworking that repairs dents, usually without painting, especially dents in the sheet metal surfaces of motor vehicles, and can also be effectively used to repair more extensive automobile body damage.
(2) Description of Related Art
Sheet metal body components of automobiles and other vehicles can become damaged in accidents, by other vehicle doors being opened in parking lots and hitting an adjacent vehicle, by shopping carts rolling into a vehicle, by hail damage from storms, and by many other occurrences. Conventionally, the art of repairing sheet metal damage, including deformities, dents and xe2x80x9cdingsxe2x80x9d (as small dents are sometimes known), has taken several forms. One common technique involves sanding or otherwise abrading the area of the dent or ding to bare the sheet metal and then filling the dent or ding with a filler material such as a substance known commercially as BONDO(copyright) (a registered trademark of Dynatron/Bondo Corporation, Atlanta, Ga.), or an equivalent material. The filled area of the dent is then smoothed by grinding, sanding, or rubbing and polishing until the damaged area is level or even with the surrounding sheet metal. The entire area is then repainted to restore its original appearance.
The color, tone and depth of the repainted area rarely matches the original factory paint finish. Even the most artistically applied repair will age or fade differently than the original finish, thus making the repair obvious. Other disadvantages include the need for sandpaper or emery cloth, and the need for surface preparation chemicals, towels and rags, paint and paint applicators.
Other conventional means to remove dents from automobile bodies include the use of a conventional tool known as a slap hammer (also known as a slide hammer) which includes a pointed tip used for engagement with an automobile body panel, such as a fender, usually by screwing it into a hole which has been previously drilled. Thereafter, a weight which is slidable upon a shaft connected to the point is used to hammer the weight outwardly to pull the body panel back into shape. U.S. Pat. No. 4,924,056 teaches a slap hammer which includes a stud welding gun to releasably grip a stud and weld it to the dent and an integral hammer means which applies force to the stud and straightens the dent. U.S. Pat. No. 4,495,791 discloses a pneumatic puller tool having a threaded point, and includes a piston for imparting a driving force against a rear cap by pressure of compressed gas and a spring used to return the piston within the tool. U.S. Pat. No. 4,072,042 discloses a pneumatic puller which includes a universal joint which allows the apparatus to cooperate with a pneumatic wrench. A harness is used to prevent the output shaft from disengagement from the universal joint.
U.S. Pat. No. 5,408,861 discloses a slap hammer which includes an internal drive, and which provides on one end an assembly for engagement with a removable self-tapping member and which provides on the other end a recess adapted for communication with an air wrench drive. The slap hammer disclosed in U.S. Pat. No. 5,408,861 eliminates undue stress on the shaft of the driver, cooperates with a pneumatic wrench, and eliminates the need for a piston. The slap hammer disclosed in U.S. Pat. No. 5,408,861 accepts and cooperates with a drill bit which includes both drill flutes and screw threads. These and other similar prior art dent repair tools require repainting after dent repair.
In the art of so-called paintless dent repair, conventional tools have a working end which can be manipulated by the user to press the damaged area and force the bent metal into alignment with its original surrounding area. However, since most dings occur in the sheet metal of doors, and/or vehicular body portions which are relatively inaccessible, or at least not readily observable with the unaided eye, it is sometimes necessary to provide a pointer which will designate a location of the hidden working end of the tool so that the repair tool can be aligned precisely and exactly on the underside of the ding. Manipulation of the tool to press or tap the sheet metal at an undamaged location could inflict more damage to the sheet metal surface because the gauge thickness of the surface is usually very thin and flexible. U.S. Pat. No. 5,479,804 discloses a tool which utilizes a laser beam instead of a mechanical pointer to designate the exact location of the working end of the tool.
Another paintless dent repair tool includes a working end having a roller bearing on the end of a steel rod. The roller bearing is manipulated by manually moving the steel rod""s roller bearing forcefully over the xe2x80x9cdingxe2x80x9d from the underside of the sheet metal.
One drawback to prior art tools and methods is the slowness involved in paintless dent repair using manual pressing or tapping tools or a manually operated roller bearing. Another drawback is the inability of workers to exert sufficient leverage in some confined or hard to reach places.
The present invention provides a tool for use in repair of dents or dings in sheet metal, particularly sheet metal portions of automobiles. The tool comprises a hand-held, preferably pneumatically-actuated, motor which contains a motor shaft that spins. A preferably elongated inner shaft is connected at its proximal end to the motor shaft, preferably by means of a threaded connection through a collet and a collet chuck, and is connected at its distal end to a working head. The inner shaft is contained within an outer shaft. The outer shaft is connected to the housing of the motor, preferably by means of a threaded collar, to allow a person to grip the motor housing with one hand and the outer shaft with the other hand in order to place the head where needed. Bushings contained within the outer shaft bear and maintain the inner shaft within the outer shaft and still allow the inner shaft to spin as the motor shaft spins. These bushings reduce eccentric movement and vibration of the spinning inner shaft. Preferably, these bushings are constructed from polymer or plastic materials, are shaped to minimize contact with the inner shaft to reduce friction, and are designed to dissipate heat generated by the spinning inner shaft and to allow fluid communication through the bushings.
The inner shaft has a proximal end which is held firmly in the collet chuck by means of a collet threaded onto the motor shaft. A working head having a central annulus is removably connected to the distal end of the inner shaft. Preferably, the working head is connected through the inner shaft to the motor through a seal and bearing on the distal end of the inner shaft or, alternatively, through a grease seal or an oil seal on the distal end. The working head is preferably stainless steel and is shaped so that, when the head spins, curved protrusions on the head can be directed against a raised surface of sheet metal to impact the damaged area and force the bent metal to restore its original alignment with its surrounding area. Since most dents and dings occur in the sheet metal of doors and/or other vehicle body portions which are relatively inaccessible, it is often necessary to have a selection of shaft sizes to allow access and leverage. To allow access within doors of automobiles, the working head can comprise a shaped end of the motor shaft or a shaped head on the inner shaft.
The working head is shaped to allow the rotational motion of the spinning inner shaft to be transmitted as repeated impact force on the raised surface of sheet metal when the head is urged against a raised damaged area of sheet metal. Preferably, the working head is shaped so that when it spins and the perimeter side thereof is urged against the raised sheet metal surface, the head xe2x80x9ctapsxe2x80x9d out the dent or ding. Leverage to force the spinning head against the raised underside of a dent or ding can be obtained either manually or by the use of chains or other supports from which the tool is suspended from the outer shaft.
The present invention is also directed to a method for repair of dented sheet metal using rotational motion of an eccentrically-shaped (i.e., out-of-round) working head, and preferably using a tool according to the invention. The method can include use of conventional pointers, including laser pointers, and conventional means for urging the head against the work piece. Accordingly, it is an object of the present invention to provide a tool and a method for repairing dents in sheet metal.
These and other objects and features of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings.